The FX6 and log exposure for commandos

[Andy9]

I shot a news feature with the FX6 last week. The spec said that shooting log was “preferred but we don’t insist”. I’d never shot log for this kind of work before but it sounded like err… fun.

The shoot day started in an outdoor dog shelter built on the side of a hill. Lots of direct sunlight so massive differences between sun and shade. Also extremely high heat and humidity. After an hour I had about an inch of dry cotton left at the bottom of my shorts, the rest was sweat patch. No problems with log. Or dogs, apart from licking - probably the sweat!

Later we filmed a long section (including an interview) in a taxi while the sun set - so constantly changing light. Final shots were urban night time and high base (or whatever Sony calls it) at f/2.8 was just about perfect. It was well handled in the edit, although I actually don’t think it needed that much work.

It occurred to me afterwards that no other camera would have handled that shoot day with quite the same ease as the FX6. Mainly because of the electronic variable ND but also the low light performance. The FX9 has the same VND but its high base ISO of 4000 (rather than 12800) might have been a problem for the final hour. The FX9’s lower high base would be preferable for 95% of even my seat-of-the pants shooting, but when you need those extra clean stops in the darkness, you really need them.

Anyway, log: I was surprised how trouble free shooting and delivering log was. I’m not sure what trouble I was expecting, I suppose I’d internalised the idea that log is better suited to controlled environments. Also it being news - I can only imagine the emails I’d get if I started delivering log footage to every news client.

The only part I had doubts about was the changeover from low to high base as the sun set. I don’t have a good sense of how other people are handling the switch between the two or what editors expect.

Which of these would best describe your approach as light fades?

1. As soon as I am underexposing low base, I would switch to high so that all of my footage is ‘correctly’ exposed and there is no way they can mess it up in post.

2. I stay on low base for a stop or two (underexposing) before I switch to high as this will produce a cleaner image if it’s properly handled in post. But it’s approximate and I don’t think about it that much.

3. I stay on low base for exactly __________ stops and I keep track of this by switching to a higher-than-base exposure index. When I’ve exceeded my EI limit of __________ I switch to high base.

4. I ask the client if I think this will be an issue and do what they say.

5. I don’t shoot log in scenarios where this could be an issue in the first place. This has been a hate read for me and I’m not sure why I got this far.

 

[Doug Jensen]

1) I did a lot of testing during production of my FX6 master class on this very topic. My advice when shooting in low light is to stay in the LOW mode as long as possible and add up to +14dB of Gain as needed. When you still can't get a good exposure at +14dB, then switch to the HIGH mode and take the Gain back down to 0dB. Then start raising the Gain again from there until you get the right exposure. I show examples in Chapter 12 of my master class.

EDIT: My mistake, that is actually how I expose for S-Cinetone. For S-LOG, I do what Dave has described in the next post.

2) NEVER under-expose LOG. It is always better to add Gain onboard the camera than to under-expose and hope to fix it in post.

3) See #1.

4) Why would I ask the client how I should run my euipment? I was hired for my knowledge and skills.

5) This scenario is a good example of where the use of LOG is a good idea. One of the best things about LOG is how malleable it is in post compared to the baked-in look of a REC709 profile.

 

[drboffa]

1) If I'm shooting Cine EI (slog3) then I will generally switch to HI as soon as I start to underexpose in LOW, if not sooner. HI base is plenty clean for most scenarios—even more so if you overexpose it a bit. I generally rate the camera at 6400 when in HI, as long as conditions allow. As an aside, I also think the noise in HI is more pleasant than that in LOW, so I'd rather be in HI if I know there's going to be some noise.

From what I've found the FX6 is much more forgiving of underexposure in slog3 than the FS7 or Fs5, but it still gets a little noisy below recommended exposure levels.

I have not yet experimented with using slog3 in Custom (i.e., adding gain in camera) on the FX6.

 

[Doug Jensen]

1) If I'm shooting Cine EI (slog3) then I will generally switch to HI as soon as I start to underexpose in LOW, if not sooner. HI base is plenty clean for most scenarios—even more so if you overexpose it a bit. I generally rate the camera at 6400 when in HI, as long as conditions allow. As an aside, I also think the noise in HI is more pleasant than that in LOW, so I'd rather be in HI if I know there's going to be some noise.

From what I've found the FX6 is much more forgiving of underexposure in slog3 than the FS7 or Fs5, but it still gets a little noisy below recommended exposure levels.

I have not yet experimented with using slog3 in Custom (i.e., adding gain in camera) on the FX6.

Dave, agree with your #1 and that is how I also do it. When I wrote my first post I was thinking about S-Cinetone rather than S-LOG. I almost never use S-LOG on my FX6, so S-Cinetone was on my mind even though this thread is about S-LOG. My mistake. The only thing I'd disagree with is your commentt that HI noise looks more pleasant than LOW noise.

 

[drboffa]

Interesting to hear that you've settled on using S-Cinetone so often, Doug. I keep returning to shooting in slog3 with Cine EI because I worry about the loss of dynamic range, but maybe I'm overthinking it. I generally think S-Cinetone looks great with some grading, so I ought to experiment with it more.

As for noise in HI vs LOW, when I did some testing early on I swore that the noise in LOW looked more like fixed pattern noise while in HI it was more random (and thus preferable, if noise was unavoidable). But I may be either misremembering or relying on flawed tests. I'll have to do some more testing. Either way the noise in both settings isn't as "film grain like" (i.e., pleasant) as that from something like an Alexa sensor but in general I don't find it distracting in the way that it was on older Sony cameras.

 

[Doug Jensen]

Yes, the noise in either mode isn't too bad. That's why, as I posted above, I don't mind cranking up the Gain to +14dB before I jump over to the HIGH mode. But when I do need the HIGH mode I have no qualms about using it. There is definitely image degradation when the HIGH mode is being used. And I think that's why Sony, rightfully so, does not call the FX6 a "dual ISO" camera. HIGH isn't as good as LOW.

I find that grading S-Cinetone is generally easier to grade than S-LOG, and gets me to the same place in Resolve with less effort. I wish I had time to do some side-by-side testing that showed the results after grading each one to a final finished image.

 

[Andy9]

1) I did a lot of testing during production of my FX6 master class on this very topic. My advice when shooting in low light is to stay in the LOW mode as long as possible and add up to +14dB of Gain as needed. When you still can't get a good exposure at +14dB, then switch to the HIGH mode and take the Gain back down to 0dB. Then start raising the Gain again from there until you get the right exposure. I show examples in Chapter 12 of my master class.

EDIT: My mistake, that is actually how I expose for S-Cinetone. For S-LOG, I do what Dave has described in the next post.

2) NEVER under-expose LOG. It is always better to add Gain onboard the camera than to under-expose and hope to fix it in post.

3) See #1.

4) Why would I ask the client how I should run my euipment? I was hired for my knowledge and skills.

5) This scenario is a good example of where the use of LOG is a good idea. One of the best things about LOG is how malleable it is in post compared to the baked-in look of a REC709 profile.

Apologies for resurrecting a zombie thread.

I might ask the client because I want the end product to look as good as possible and I don’t have control of the editing stage so how they are going to treat my footage, and how much effort they are going to put in might change they way I shoot. If, for example, in answer to my questions about log they said “Oh we just stick a LUT on it and call it a day” I would shoot something other than log.

And about NEVER underexposing log - In a quick pre-shoot test I did recently, underexposing LOW by a stop and raising levels in post was cleaner than jumping straight up to HIGH (exposed as Sony recommends, I didn’t test with an offset). It was a rough test that I didn't double check as I wasn't particularly surprised. My experience is similar to Dr Boffa’s in that log from the FX6 seems way more tolerant of underexposure than with previous Sony cameras like the FS5.

 

[Doug Jensen]

Welcome back. I was beginning to think this was one of those threads where the OP asks a bunch of questions and then is never heard from again.

And about NEVER underexposing log - In a quick pre-shoot test I did recently, underexposing LOW by a stop and raising levels in post was cleaner than jumping straight up to HIGH (exposed as Sony recommends, I didn’t test with an offset). It was a rough test that I didn't double check as I wasn't particularly surprised. My experience is similar to Dr Boffa’s in that log from the FX6 seems way more tolerant of underexposure than with previous Sony cameras like the FS5.

Yes, the FX6 is better at underexposure (and everything else) than the FS5 because it a far, far superior camera. The FS5 isn't even a 10-bit camera in 4K.

May I ask what your levels are for correct exposure, and for one-stop under? Where are you putting middle gray, or white, or whatever?

 

[Andy9]

May I ask what your levels are for correct exposure, and for one-stop under? Where are you putting middle gray, or white, or whatever?

I have the s709 LUT on the LCD and expose for whites at 77. I tested a stop under by closing the aperture a stop.

 

[Doug Jensen]

If that is the case, then I would say your "normal" exposure @ 77 is already way underexposed.
When you exposed the LUT at 77, where did that put the unLUTed whites that were actually recorded?

 

[Andy9]

If that is the case, then I would say your "normal" exposure @ 77 is already way underexposed.
When you exposed the LUT at 77, where did that put the unLUTed whites that were actually recorded?

61 - which is where Sony recommends, right?

 

[Doug Jensen]

Yes, technically 61 would be correct according to Sony's ecommendations. But I would say you are underexposed. Nobody I work with anywhere in the world exposes S-LOG at 61. Most people are someplace betwen 70-75. 61 can be okay if someone really nails the exposure exactly correct, but it is right at the precipice of being underexposed. And despite your testing, underexposing S-LOG is the worst thing you can do. That is common knowledge. Exposing a little higher around 70-75 allows plenty of cushion without any penalty. 75 grades out beautifully with no downside. So why run along the edge of a cliff where one misstep will send you falling into the abyss, when you can move to the side a few feet and have some margin for error without any penalty for doing so?

If you are using the built-in s709 LUT, try setting Zebra 2 for 88 and see if you like that exposure better in post. That will put the actual recorded S-LOG around 72 and should grade out nicely with less need for being perfect all the time. Just a suggestion.

 

[Andy9]

I used to shoot log 1.5 stops over with the FS5 but changed when I switched to the FX6. I currently overexpose HIGH by a stop (77 zebras, with an EI of 6400) but I stopped routinely doing the same for LOW as there didn’t seem to be a need.

As I said previously, this is based on very cursory testing and informal experience. At the same time, I'm pretty sure I'm not alone in shooting log without a 1-1.5 exposure offset with this generation of Sony cameras. Of course, you're correct that for the vast majority of shooting situations it's a gain (less noise) for very little cost (loss of redundant DR). I just haven't had a problem with noisy footage.

"So why run along the edge of a cliff where one misstep will send you falling into the abyss" The only time I feel a sense of danger is in a low-key, low-light situation like a nighttime street scene but then I'm in HIGH anyway and over by a stop.

"And despite your testing, underexposing S-LOG is the worst thing you can do. That is common knowledge" Have you actually tested recovering an underexposed Slog3 image from an FX6 or a7Siii at low base? I'd still rather be over than under in most shooting situations, but under by a stop or even two is not the disaster it used to be.

"If you are using the built-in s709 LUT, try setting Zebra 2 for 88 and see if you like that exposure better in post" I might revisit this on my next shoot and do a bit more testing in LOW.

1) If I'm shooting Cine EI (slog3) then I will generally switch to HI as soon as I start to underexpose in LOW, if not sooner. HI base is plenty clean for most scenarios—even more so if you overexpose it a bit. I generally rate the camera at 6400 when in HI, as long as conditions allow. .

Dr Boffa, when you say that you "rate the camera at 6400" how are you then judging exposure?

 

[Doug Jensen]

I Have you actually tested recovering an underexposed Slog3 image from an FX6 or a7Siii at low base?

Absolutely. I've tested S-LOG3 on the FX6 in LOW and HIGH modes from 50 IRE up to 90 IRE in 5 IRE increments using a Leader LV5330 waveform monitor to ensure precision. Then bringing the footage into Resolve and judging it after final grading.

I have no interest in the A7Siii.

 

[drboffa]

Dr Boffa, when you say that you "rate the camera at 6400" how are you then judging exposure?

I almost always use an external monitor and waveform; if I need to be really precise I will also use a light meter, but that's limited to more controlled situations.

 

[Andy9]

I almost always use an external monitor and waveform; if I need to be really precise I will also use a light meter, but that's limited to more controlled situations.

Thanks, and do you have a target level for reflected white / mid grey?

 

[Doug Jensen]

Thanks, and do you have a target level for reflected white / mid grey?

Yeah, that's the number that really matters and that people hardly ever mention unless you squeeze it out of them. All the talk of rating the camera at __ EI, __ ISO, ETTR, exposing __ stops over, etc. is all nonsense compared to just knowing the IRE target level you are aiming for. If you didn't hit the target, then you are underexposed. If you went over, then you are overexposed. Easy.

The fact is, a lot of people (not pointing at anyone on this thread) have no idea what target they are aiming for, so you get dumb **** like exposing for caucasian skintones or pushing stuff just to the edge of clipping.

 

[drboffa]

Thanks, and do you have a target level for reflected white / mid grey?

Anywhere in the 70s for white and I'm happy. I have some grey cards but I don't know that I trust them to be accurate enough representations of middle grey to really rely on them.

I should also add that I've recently switched over to S-Cinetone in some fast-paced scenarios, especially if I know I won't be doing the grading myself or if I want to make my grading work easier/faster. Not to hijack the thread, but I'd be curious to hear from Doug where he's putting grey / whites when exposing S-Cinetone. It's been over a year since I watched the Master Class so I don't recall if those numbers are discussed there.

 

[JimGao]

(edit, i sort of regret this joke, but after it got taken seriously, I sort of ran with it for a bit, but since no one was getting it, i just left it alone. Hopefully Doug’s responses to these next few comments help someone else out, he’a a good teacher, but mostly dvxuser has only old vets and self employed shooters, so there idk who needs to read these, but hopefully it gets you a chuckle)

Do grey cards work? i put an 18% grey card at 18%IRE and it was overexposed by quite a lot.

 

[ahalpert]

Fwiw I think one can probably develop a better in-camera look designed for no or little grading than s-cinetone. I prefer what I've developed to s-cinetone